+1 to this. When a dealer I respect says a coin is PQ, I pay attention to that. When some shlub on eBay says a coin is PQ+++, I hit the back button.
I try not to call it anything but have been known to call it "corrosion" or just "green" in context. "I have to get the green off my old copper coin". I'm not sure what I don't like about the word. Mebbe it just took too long to figure out its meaning.
Thinking about it, the term "rare" annoys me when used out of context. Especially on vam or semi-key cull morgan listings on ebay
The terms that irritate me the most? Error, when applied to a coin such as a die crack or clash. The coin is NOT an error even if it is called so by error specialists--on the contrary, it is exactly what should be expected from using a die in that particular stage of its normal life. Nor is such a coin a different variety. Therefore, it should not be listed as such in texts like the Red Book even if it does have a fancy nickname such as "The Bearded Goddess". Edit to add: Yes, I know that this is an argument that I'm never going to win, but hopefully I can continue it for another 50 plus years.
I prefer no particular term at all for the coin. It is exactly what it purports to be...a coin in a given series/MM....just like the coins struck from that die prior to the die cracking/clashing Coins displaying die cracks/clashes are interesting as a study of the normal life of a die pair, but that's my point. It is simply a normal part of the minting process--not an error.